1. Field of the Invention
The present invention relates to a reactive polyolefin composition where a functional group is introduced into a chemically inert polyolefin, a molding thereof and a process for producing the same. More particularly, the present invention relates to a polyolefin molding which is capable of easy secondary processing such as coating, printing or the like, and a process for producing such a molding.
2. Description of the Prior Art
Heretofore, since polyolefins have no polar group nor active group showing reactivity in their molecular structure, and are poor in a solubility in solvents, it has been difficult to secondary process the same, such as bond, print, coat, dye or the like a surface of a molding thereof. As a result, various special surface treatments have been employed to apply secondary processings as mentioned above to the surface of a polyolefin molding.
In printing, a flame-treatment, a corona discharge treatment or the like is generally employed, but these techniques involve the disadvantages that the shape of the moldings processable is restricted, and the surface activity obtained is not sufficient. Further, they involve the defect that the type of ink used is restricted. Therefore, the moldings thus treated cannot be coated from the standpoint of practical use.
In bonding, a technique is known where the surface of a molding is oxidized with a chromium acid-sulfuric acid mixed solution; however, in this known method there are disadvantages such that dangerous chemicals are used, operations are complicated and the treated surface loses luster. Further, local oxidation is difficult. Therefore, the molding thus treated cannot be coated from the standpoint of practical use.
In coating, there are paints for polyolefins which do not require the surface treatments mentioned above for use. There are two types of such paints, one where a resinous undercoating primer is necessary and another where a single coating of paint can be used which does not require the use of a primer. However, there are difficulties in that since the primer is expensive, the paint which requires the use of a primer involves high material costs and high coating costs, and since the latter paint (not requiring the use of primer) is a specific paint, the properties of the paint film are restricted.
In addition, in order to impart activity to a polyolefin other techniques have been attempted: the copolymerization of an olefin with a comonomer having a functional group, such as vinyl acetate, or acrylic acid; the hydrolysis of a copolymer of an olefin and vinyl acetate; or the graft polymerization of an olefin with acrylic acid or acrylic anhydride, etc. However, the functional group introduced does not show activity under normal conditions and only shows activity upon melting for bonding to a metal, glass fiber or the like. Therefore, a molding of such modified polyolefins cannot be coated with general paints, and, in many cases, the physical properties of the modified material are remarkably different from the inherent physical properties of the original resin.